When an image to be displayed on a high-resolution display lacks resolution, the image needs to be enlarged to be suitable to the resolution of the display.
Techniques of increasing resolution of an image have long been proposed. However, a simple combination of interpolation enlargement processing and enhancement processing has been employed for the practical realization due to restriction on the processing amount. Therefore, there has been a problem of image degradation such as highly visible blurring or jaggies on edges.
Recent advancement in hardware sophistication has allowed increased processing amount for enlarging an image. This leads to attention drawn on a “super-resolution technique” which enables high-definition resolution conversion through complicated processing.
Among the super-resolution techniques, a method which uses a database based on learnt cases of the correspondence relationship between a high-resolution image and a low-resolution image is called a training-based system (see, Patent Literature 1, for example).